This invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument of a type wherein voltage-controlled type circuits are employed to control tone pitch, tone color and volume of a musical tone.
In an electronic instrument of a type which is called a music synthesizer, voltage corresponding to the tone pitch of each key on a keyboard (hereinafter referred to as "pitch voltage") is produced in response to depression of the key. Controlling a voltage-controlled type oscillator by this pitch voltage, a tone source signal of a frequency corresponding to the pitch of the depressed key is produced. The pitch voltage corresponding to each key is determined in a suitable circuit such as a voltage dividing circuit. The pitch voltage, however, is fixedly determined in accordance with a regular tone pitch of a selected temperament, e.g., an equal temperament, and cannot be changed. Accordingly, a musical scale obtainable from a conventional musical synthesizer is limited to one of a temperament preset in a pitch voltage generation circuit, e.g., an equal temperament scale.
Since the pitch voltage of each key is fixedly determined in accordance with a predetermined temperament scale, a musical tone element for control of which the pitch voltage is utilized is extremely limited. More specifically, the pitch voltage has heretofore been utilized only for controlling the cut-off frequency of a voltage-controlled type filter except for the aforementioned oscillation of the tone source signal.